Biomass
Practical Action
Briquettes made without a binder are partially carbonised or not carbonised at all. The drawback
is that the pressure has to be increased and the equipment used is more complicated.
Most waste materials can be burnt directly without being briquetted beforehand. Sawdust stoves
and rice husk stoves are relatively common; see the Stoves for Rice Husk and Other Fine
Residues technical brief.
Dung collection
Many poor families in rural and
urban areas use animal dung as a
fuel source or collect dung as
their source of income. There is a
group of women in Bangladesh,
who traditionally collect dung,
make cakes and sell them to
commercial markets. The
traditional collectors of dung are
teenage girls from poor families.
They bring back dung to their
homes and convert it into round
cakes and cone-like sticks for
drying in the open air.
Figure 5: A woman putting cow dung onto sticks prior to
drying. These will be used as fuel, Bangladesh. Photo: Zul
Mukhida / Practical Action.
Dung is considered to be one of the best fuels for the traditional mud stove for the
following reasons
it burns slowly
cooks fast
generates powerful heat compared to other sources of fuel found locally
easy to store
Less toxidity
Problems related to dung as a fuel are;
there is a scarcity of dung
cattle owners do not permit collection form their fields
as dung is being dried there is a risk that it could be stolen
It burns faster than wood when it is not properly compressed
Source: Mohammed Aslam, Practical Action Bangladesh
The alternative approach to using cow dung and other animal waste is the biogas digester which
will produce gas that can be used for cooking and lighting or to generate electricity. It will cost
more money to implement and maintain.
Other issues
Commercial utilisation of biomass
Biomass can be used for a variety of commercial activities. There are several technologies which
employ direct combustion of unprocessed or semi-processed biomass to produce process heat
for a variety of end-uses. The most common is the simple furnace and boiler system which raises
steam for such applications as electricity generation and beer brewing. Biomass is also used to
provide direct heat for brick burning, for lime burning and cement kilns. The advantage of using
biomass is that it can be locally sourced, thereby avoiding shortages associated with poor fuel
supply networks and fluctuating costs. Rice husk has been used as a heating source for drying in
Sri Lanka; see the Anagi Tray Dryer technical brief.
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